1. Field of the Invention
The present invention relates to a novel negative type photosensitive resin composition and a method for forming a resist pattern.
2. Description of the Related Art
A negative type photosensitive resin composition has excellent characteristics in points of no environmental pollution, the saving of resources and energy, high production efficiency and the like, and for this reason, the composition has heretofore been used as a coating composition, an ink and an adhesive in many fields. This kind of photosensitive resin composition has been applied to use purposes in which circuit boards, plastics, lumbers, metals, papers, glasses, fibers and the like are used as materials.
However, when such a negative type photosensitive resin composition is industrially produced and applied to a practical application, the following problems are present.
Nowadays, there have been used many photosensitive resin compositions which react with the aid of a photoreaction initiator activated by a visible light to form a cured film.
For an emission spectrum wavelength of the visible light which has heretofore been used for the curing, activated lights of 488 nm, 532 nm and the like have been usually used. In the case that such a negative type photosensitive resin composition is handled, an electric lamp such as a fluorescent lamp colored by coating an outer tube of the lamp with a dark red colorant or by winding a dark red film around the outer tube is used as a safelight (a working lamp). Under the environment of such a dark red safelight, however, some problems are present. For example, it is difficult to inspect the state of a coating film after the coating, and it is not easy to check a coating apparatus, an irradiation apparatus, a conveying apparatus and the like. In consequence, safe working properties, working efficiency, quality stability of products and the like are poor. In addition, in the case that an uncolored fluorescent lamp is used as the safelight, the working environment is illuminated and there are not the above-mentioned problems any more, but even portions where the exposure is not required might be exposed inconveniently, depending on the kind of photosensitive resin.